1. Field of the Invention
This invention relates to a target shape portion cutting apparatus and method of cutting out a target shape portion formed on a metal sheet from the remaining portion thereof, and a robot equipped with the target shape portion cutting apparatus.
2. Description of the Related Art
For cutting out a target shape portion from a metal sheet, the metal sheet is first worked so that the target shape portion, a portion surrounding the target shape portion (the surrounding portion being hereinafter called xe2x80x9cbase metal sheetxe2x80x9d) and at least one elongated joint portion for joining the former two portions are formed on the metal sheet, and then the joint portion is cut out, using:
(a) a method of mechanically applying an impact or vibration to a portion near the joint portion to thereby cause plastic deformation so that a link portion between the target shape portion and the base metal sheet is cut out;
(b) a method of cutting out the target shape portion by a finishing machine without leaving any joint portion, and drop the target shape portion on a conveyor or the like for collection of the target shape portion; or
(c) a method of using a robot mounting a target shape portion cutting apparatus equipped with a scissors-like tool (nipper), which causes the tool to approach vertically to the joint portion between the target shape portion and the base metal sheet, from above, so that the blade of the tool abuts on the top surface of the joint portion to thereby snip off the joint portion in the plane direction.
Since the above method (a) applies an impact or vibration to the joint portion, burrs are produced on the portion where the target shape portion has been cut out. Therefore, post processing, such as burr removal, is therefore needed after separating the target shape portion. Further, since the position and posture of the target shape portion after separation are not stable, it is difficult for the robot to hold and take away the cut-out target shape portion. This makes it difficult to achieve automation of working metal sheets, remote manipulation of the robot and so forth.
The above method (b) likewise causes unstable position and posture of the target shape portion after it is cut out. Therefore, like the method (a), the method (b) makes it difficult for the robot to hold and take away the cut-out target shape portion. This makes it difficult to achieve automation of working metal sheets, remote manipulation of the robot and so forth.
Since the above method (c) cuts out the joint portion formed on the metal sheet by the tool, such as the nipper, a hole large enough for allowing the free end of the tool to enter has to be formed in an area around the joint portion of the metal sheet. Further, since the tool (nipper) moves in the widthwise direction of the joint portion to cut out the joint portion, a part of the joint portion remains on the cut-out target shape portion. Therefore this method requires post-processing for removing the remaining portion of the joint portion. Further, separation of the target shape portion cannot be confirmed based on only the tool movement. Moreover, it is difficult to take out a cut-out target portion because a portion of the joint portion remaining on the target shape portion may interfere with a portion of the joint portion remaining on the base metal sheet when cutting out and taking out the target shape portion. In addition, as the free end of the tool goes through a tool insertion hole formed in the metal sheet and protrudes further below the bottom surface of the metal sheet when the target shape portion is cut out, the tool may cut the member which supports the metal sheet.
An object of the present invention is to provide a target shape portion cutting apparatus and method that are designed in such a manner that when a target shape portion formed on a metal sheet is cut out from the remaining portion of the metal sheet, the results of the separation require no post-processing and do not interrupt taking out of a cut-out target shape portion.
To achieve the abovementioned object, with a metal sheet which has been worked in such a way that a target shape is connected to a base metal through one or a plurality of joint portions by forming a hole at a region adjacent to the joint portion, a target shape portion cutting apparatus according to one aspect of the present invention comprises a first member having a first blade for pressing a boundary portion between the target shape portion and the joint portions of the perforated metal sheet from one face of the perforated metal sheet and from the side of the target shape portion; and a second member having a second blade which approaches the joint portion from the other face of the perforated metal sheet, grips the boundary portion in association with the first blade in a thickness direction of the perforated metal sheet and shears the perforated metal sheet at the boundary portion to thereby cut the target shape portion off a joint portion.
The second member having the second blade is supported in a manner such that it rotates relative to the first member having the first blade and is driven by a cylinder or a motor. Alternatively, the second member having the second blade is moved by a cylinder or a motor in the thickness direction of the perforated metal sheet relative to the first member having the first blade and cuts the target shape portion off a joint portion. The second member having the second blade is thick enough to be able to bend a joint portion by pushing it at the time of cutting out the target shape portion from the joint portion.
A robot may mount the target shape portion cutting apparatus to cut a target shape portion of a metal sheet off a joint portion which connects the target shape portion to a base metal sheet.
A method of cutting out a target shape portion from a base metal sheet using the robot comprises a step of placing a metal sheet having the target shape portion connected to the base metal sheet with one or a plurality of joint portions on a mounting section whose surface member is made of a soft material or a brush-like material soft enough to be able to keep a plane posture of the target shape portion and the base metal sheet; a step of pressing an exposed region of the mounting section with the second member having the second blade through a tool insertion hole formed adjacent to the target shape portion to be cut out; a step of moving the second blade under the joint portion to be cut out from the target shape portion while pressing the mounting section with the second member having the second blade; a step of pressing a boundary portion between the target shape portion and the joint portion with the first blade positioned above the joint portion, from the side of the target shape portion; and a step of moving the second blade upward to snip off the joint portion in association with the first blade.